A thiazole derivative is a useful compound as a functional compound (or a synthesis intermediate thereof) such as an agricultural chemical (insecticide, etc.), a medical product, a fungicide and a dye, and an electronic material. Examples thereof include a thiazole derivative that is a compound having a thiazole skeleton used as an interleukin-6 production inhibitor/bone absorption inhibitor/anti-osteoporosis agent (Patent Document 1), a thiazole derivative used as a bone forming accelerator (Patent Document 2), a thiazole derivative used as a protein kinase C inhibitor (Patent Document 3), a thiazole derivative used as an agricultural chemical intermediate (Patent Document 4), and a thiazole derivative used as a neuropeptide Y antagonist (Patent Document 5).
In these documents, various methods are disclosed as synthesis examples of thiazole derivatives. For example, bromine is dropped into a dichloromethane solution of 4′-chloropropiophenone to be acted and the mixture is then reacted with thiourea (Patent Documents 1 and 2), a method of adding 3-chloroacetylacetone to an ethanol solution of thiourea and reacting with heating, and then adding a poor solvent to be deposited by cooling (Patent Document 3), a method of mixing difluorophenacyl bromide and cyanothioacetoamide in water to be reacted with heating (Patent Document 4), and a method of mixing β-acetonaphtone and thiourea, and tetrabutylammonium bromide in ethyl acetate and dropping bromine thereinto to be reacted (Patent Document 6). These methods respectively remain rooms for improvements with respect to using bromine that has a pungent odor, with respect to necessity of obtaining particular reagents, and the like.
On the other hand, a pyridyl thiazole compound that is one of thiazole derivatives is useful as a fungicidal composition, and a production process thereof is described in the following document (Patent Document 7). According to the document, 2,6-dibromopyridine is treated with alkyl lithium and N,N-dimethyl acetoamide is then added thereto. The reaction mixture is brominated with a brominating agent in the presence of an acid and then reacted with thioacetamide and, finally by a coupling reaction with alkyl halogen, a desired pyridyl thiazole compound is thus obtained. This process includes a step with multiple stages and thus has a problem with respect that an operation method thereof is somewhat complicated.
Furthermore, for a preparation process of dihydrothiazole (referred to as thiazoline in IUPAC, and referred to as dihydrothiazole in order to clarify difference from thiazole in the present invention) that is one of thiazole derivatives, proposed is, for example, a method of mixing methyl 2-(difluoromethyl)-5-(((2-chloroethyl)amino)carbonyl)-4-(2-methylpropyl)-6-trifluoromethyl)-3-pyridinecarboxylate and diphosphorus pentasulfide with heating and degassing to produce dihydrothiazole (Patent Document 8). In this method, a particular starting substance is required in order to obtain a 4,5-dihydrothiazole compound having a pyridyl group at the 2nd position.